This was proven by linking C2 to 3L carrying Sh2 with a translocation and the heterozygote was then crossed by and on a c2 sh2 tester. All the colorless sectors on the variegated kernels from the outcross ears were also sh2 indicating the loss of both markers.
Therefore, this mutant is designated C2-b for C2 breaker. System tests indicate that this mutant does contain many Cy and En but neither show a correlation with the occurrence of breakage. This breakage may be under control of a previously undefined element.
Two mutable derivatives have been isolated from this mutant.
c2-m881058P: An exceptional spotted kernel (2-5 a-b) was found on an ear segregating colored, variegated and colorless. The kernel (c2-m/c2) was selfed and outcrossed several times to c2/c2 testers. The spotting phenotype was heritable and segregated 45 spotted:19 colorless from the self and 3 spotted:5 colorless from the outcrosses. This mutant allele was designated c2-m881058P and seems to be controlled by two independently segregating functional elements. The spotted kernels from the outcrossed ears segregated for three distinct phenotypes: 1 high (6-8 aa-d):1 low (2-6 aa-b):1 extreme low (1-3 aa-a). It may be that each of the two independent regulators causes a different spotting pattern in this c2-m allele and both regulators acting together elicit a third spotting phenotype. This can be verified by further testing.
c2-m881058Y: Another exceptional spotted kernel (5 b-c) was found on an ear segregating colored and colorless from C2-b857246. This mutant was found to be heritable, designated c2-m881058Y and also seems to be under control of two independently segregating regulators. The spotting phenotype is heavy (5-7 a-c) with occasional (1%-14%) low (1-4 aa-a) spotted kernels appearing. This lower spotting phenotype may be due to a change of state of the c2-m allele or to changes to one or the other or both independent regulators.
A study of the relation of c2-m881058P
and c2-m881058Y to each other and to C2-b857246 is in progress.
Also, studies on the cause and heritability of the lower spotting patterns
and system tests are in progress.
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